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*EJM157*

EJM – 157

I Semester M.E. ( Control & Instrumentation) Degree Examination, March 2013 (2K8 Scheme) SENSORS IN INSTRUMENTATION (Elective – I) Time : 3 Hours

Max. Marks : 100

Instruction : Answer any five full questions. 1. a) What is a sensor ? Explain the following terms related to a sensor i) Accuracy ii) Calibration iii) Saturation iv) Dead band.

8

b) How transducers are classified ? What are the basic requirements of a transducer ?

6

c) Explain resistance temperature characteristics of metal alloys.

6

2. a) Explain the laws governing the rate of transfer of heat by different modes.

8

b) What is an anemometer ? Explain i) Constant resistance type anemometer ii) Constant current type anemometer.

12

3. a) What are strain gauges ? How strain gauges are classified ?

6

b) What are semi conductor strain gauges ? What are their advantages ? Explain the effect of variation in doping level.

8

c) Explain the Wheatstone circuit for strain measurement.

6

4. a) How resistance transducers help us to measure moisture ? Explain moisture measurement setup. 10 b) Explain, with sketch, the measurement of linear and angular displacement using solenoid coil.

10 P.T.O.

*EJM157*

EJM – 157 5. a) Explain NULL voltage compensation circuits used for LVDT.

6

b) What is a proximity transducer ? How it is used in practice ?

6

c) What is piezoelectric phenomenon ? Explain how it can be used to detect i) Force ii) Torque ?

8

6. a) What are ion selective electrodes ? Explain their different types.

10

b) Explain the operation with sketch the position sensitive detector sensor. 7. Write short notes on the following : i) Pirani vacuum gauge ii) Hall effect transducers iii) Seismic displacement transducer iv) Fibre optic sensor.

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10

(5×4=20)